In our studies of the biophysical processes underlying memory formation in mice, we are attempting to determine which neurotransmitters are involved in memory trace formation, and specifically what role they play. Current experiments are testing the effects of drugs that alter dopamine, norepinephrine, serotonin and acetylcholine on retention. In addition, our work with protein synthesis inhibitors is testing if neurotransmitters and ribosomal protein synthesis have distinctly different functions in memory trace formation. Other experimental work involves determining the regions of the brain which mediate drug effects on retention in an effort to define the neuronal substrate most important for the early phases of memory trace formation.